A copper-decorated porous graphite carbon shell-wrapped iron catalyst, a preparation method therefor, and applications thereof

Abstract

The application discloses a copper-decorated porous graphite carbon shell-wrapped iron catalyst and a preparation method and application thereof, the catalyst taking an iron nanosphere as a core, being wrapped with a porous graphite carbon shell on the surface, and loading copper metal nanoparticles on the shell surface. The copper-decorated porous graphite carbon shell-wrapped iron catalyst provided by the application has a lower thermal conductivity and good thermal stability due to the graphite carbon shell, can effectively isolate heat conduction, and maintains the stable temperature of the catalyst particles, which helps to reduce the heat loss in the sintering process, improves the sintering resistance and heat preservation of the catalyst, and reduces the heat loss in the reaction process. In addition, the copper nanoparticles are decorated on the outside of the carbon shell, the local surface plasmon resonance effect and high thermal conductivity of the copper nanoparticles are utilized, the photo-thermal conversion performance of the catalyst is improved, and the yield of CO2 hydrogenation and the selectivity of high-value-added compounds such as olefins are promoted.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of catalysts, in particular to a copper-decorated porous graphite carbon shell-wrapped iron catalyst, a preparation method and application thereof. BACKGROUND

[0002] The continuous combustion of fossil fuels and the emission of greenhouse gases have caused a series of global problems such as energy shortage, environmental pollution, and climate warming. At present, the resource utilization of carbon dioxide is an effective solution. Using solar energy and photocatalytic materials to convert CO2 into CO, CH4, CH3OH and other high-value chemical fuels not only has important significance in the field of clean energy, but also plays a crucial role in stabilizing and reducing the content of carbon dioxide in the atmosphere, thereby slowing down the greenhouse effect.

[0003] Photothermal catalysis requires the conversion of solar energy into heat energy to drive the reaction. A high-efficiency photothermal CO2 hydrogenation system requires the synergistic effect of strong broadband solar energy absorption, effective photothermal conversion, heat preservation ability, and high catalytic activity and selectivity. Selecting good heat-conducting materials and heat-preserving materials can effectively utilize the heat effect generated by light, improve the photothermal conversion efficiency, save energy, and achieve higher economic value.

[0004] However, the efficiency of photothermal conversion is relatively low at present, which limits the efficiency and yield of the catalytic reaction. Secondly, although many catalysts have been developed to promote the CO2 hydrogenation reaction, there is still room for improvement in their selectivity and activity. At present, reducing the formation of alkanes and improving the selectivity of olefins in the process of preparing olefins from CO2 hydrogenation is the focus of research. SUMMARY

[0005] The main purpose of the present application is to provide a copper-decorated porous graphite carbon shell-wrapped iron catalyst and a preparation method and application thereof, aiming to solve the problems of low photothermal conversion performance, easy sintering at high temperature, and wide product distribution of existing iron-based catalysts in the carbon dioxide hydrogenation reaction.

[0006] To achieve the above-mentioned purpose, the present application provides a copper-decorated porous graphite carbon shell-wrapped iron catalyst, which takes iron nanospheres as the core, is wrapped with a porous graphite carbon shell on the surface, and loads copper metal nanoparticles on the surface of the shell.

[0007] The present application also provides a preparation method of the copper-decorated porous graphite carbon shell-wrapped iron catalyst as described above, comprising the following steps:

[0008] S1, dissolving a carbon precursor in deionized water to obtain a solution A;

[0009] S2, adding a precursor iron salt and an alkali catalyst to the solution A, aging, cooling, centrifuging, and drying to obtain a solid particle A;

[0010] S3, dissolving the solid particles A and a template agent in a solvent, stirring, centrifuging, washing, drying, calcining to obtain Fe@C;

[0011] S4, dispersing the Fe@C into methanol, adding a copper salt, stirring vigorously at room temperature, centrifuging and drying, and calcining to obtain a copper-decorated porous graphite carbon shell-encapsulated iron catalyst.

[0012] Optionally, in step S1, the carbon precursor is one selected from dopamine, glucose, sucrose, and chitosan; and / or,

[0013] The carbon precursor and deionized water are used in a ratio of (100-200 mg) to (20-40 mL).

[0014] Optionally, in step S2, the precursor iron salt is one or more selected from ferric nitrate, ferric nitrate hydrate, ferric chloride, ferric chloride hydrate, ferric acetate, ferric acetate hydrate, ferric sulfate, ferrous sulfate, and acetylacetone iron; and / or,

[0015] The carbon precursor and the precursor iron salt are used in a ratio of (100-200 mg) to (35.5-70 mg); and / or,

[0016] The base catalyst is one selected from ethylenediamine and concentrated ammonia; and / or,

[0017] The base catalyst and the precursor iron salt are used in a ratio of (50-100 μL) to (35.5-70 mg); and / or,

[0018] The aging temperature is 160-200°C, and the aging time is 2-6 h; and / or,

[0019] The centrifugation speed is 6000-10,000 rpm, the centrifugation time is 5-10 min, and the centrifugation number is 2-3 times; and / or,

[0020] The drying temperature is 60-80°C, and the drying time is 12-24 h.

[0021] Optionally, in step S3, the template agent is one or more selected from a mixture of 1,3,5-trimethylbenzene and polyethylene-polypropylene ether copolymer, polystyrene beads, and polypropylene microspheres; and / or,

[0022] The solid particles A and the template agent are used in a ratio of (0.5-1 g) to (1-2 g).

[0023] Optionally, the template agent is a mixture of 1,3,5-trimethylbenzene and polyvinyl-polypropylene ether copolymer, and the ratio of the amount of 1,3,5-trimethylbenzene to polyvinyl-polypropylene ether copolymer is (2.0-4.0 mL):(1-2 g).

[0024] Optionally, in step S3, the solvent is toluene or a mixture of water and ethanol; and / or,

[0025] The stirring speed is 500-600 rpm, and the stirring time is 30-40 min; and / or,

[0026] The centrifugation speed is 6000-10,000 rpm, and the centrifugation time is 5-10 min; and / or,

[0027] The washing is washing with water and ethanol for 3-5 times in turn; and / or,

[0028] The drying temperature is 60-80°C, and the drying time is 12-24 h; and / or,

[0029] The calcination gas atmosphere is one of nitrogen and argon; and / or,

[0030] The calcination temperature is 600-1000°C, and the calcination time is 2-4 h.

[0031] Optionally, in step S4, the copper salt is one or more selected from copper nitrate, copper nitrate hydrate, copper chloride, copper chloride hydrate, copper acetate, copper acetate hydrate, copper sulfate, and copper acetylacetone; and / or,

[0032] The ratio of the amount of Fe@C to methanol is (0.1-0.2 g):(35-70 mL); and / or,

[0033] The ratio of the amount of Fe@C to copper salt is (0.1-0.2 g):(1-4 mmol).

[0034] Optionally, in step S4, the stirring time is 24-48 h; and / or,

[0035] The centrifugation speed is 5000-10,000 rpm, and the centrifugation time is 5-10 min; and / or,

[0036] The drying is vacuum drying, the drying temperature is 60-80°C, and the drying time is 12-24 h; and / or,

[0037] The calcination gas atmosphere is argon, the calcination temperature is 800-1000°C, and the calcination time is 2-4 h.

[0038] The application also provides an application of the copper-decorated porous graphite carbon shell-encapsulated iron catalyst or the copper-decorated porous graphite carbon shell-encapsulated iron catalyst prepared by the preparation method.

[0039] Compared with the prior art, the application has the following beneficial effects:

[0040] (1) The copper-decorated porous graphite carbon shell-encapsulated iron catalyst provided by the application reduces heat loss in the reaction process by using the heat preservation effect of the carbon shell. In addition, copper nanoparticles are decorated on the outside of the carbon shell, and the light-heat conversion performance of the catalyst is improved by using the localized surface plasmon resonance effect and high thermal conductivity of the copper nanoparticles, thereby promoting the yield of CO2 hydrogenation and the selectivity of high-value-added compounds such as olefins.

[0041] (2) The copper-decorated porous graphite carbon shell-encapsulated iron catalyst provided by the application can effectively isolate heat conduction and maintain the stable temperature of the catalyst particles due to the low thermal conductivity and good thermal stability of the graphite carbon shell, thereby helping to reduce heat loss in the sintering process and improving the sintering resistance and heat preservation effect of the catalyst. In addition, the porous structure of the carbon shell may allow the series catalytic reaction, so that small molecular reactants and products can penetrate into the shell layer. The nanosphere catalyst structure is novel and has superior catalytic performance, thereby promoting the carbon dioxide hydrogenation reaction.

[0042] (3) The copper-decorated porous graphite carbon shell-encapsulated iron catalyst synthesized by the application is used for photothermal carbon dioxide hydrogenation experiments. The Cu nanoparticles have a localized surface plasmon resonance effect, thereby promoting the light-heat conversion performance. The size of the Cu nanoparticles is small enough, a part of which is in direct contact with the carbon shell, and the RWGS reaction (reverse water gas shift reaction) is carried out on the Cu nanoparticles to generate CO, which enters the Fe5C2 to carry out the FTs (Fischer-Tropsch synthesis) reaction through the pores. A part is in direct contact with the core to form a Cu-Fe5C2 interface site, in which the Cu + can promote the reduction and carburization of the Fe phase, has high CO2 conversion rate and long-chain hydrocarbon selectivity, promotes carbon-carbon coupling while inhibiting catalytic hydrogenation, improves the reaction activity while regulating the product selectivity to generate heavy olefins, and has excellent performance. BRIEF DESCRIPTION OF DRAWINGS

[0043] In order to more clearly illustrate the technical solutions in the embodiments of the application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description only show some embodiments of the application, and for those skilled in the art, other related drawings can also be obtained without creative labor.

[0044] Figure 1A structural model diagram of the catalyst obtained in Example 1 of the present application.

[0045] The purposes, functional features and advantages of the present application will be further illustrated in conjunction with the embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0046] In order to make the purposes, technical solutions and advantages of the embodiments of the present application more clear, the technical solutions in the embodiments of the present application will be clearly and completely described below. If the specific conditions are not specified in the embodiments, the conventional conditions or the conditions suggested by the manufacturers are adopted. If the reagents or instruments used are not specified by the manufacturers, they are all the conventional products that can be purchased in the market. In addition, the meaning of "and / or" appearing in the whole text includes three parallel solutions. Taking "A and / or B" as an example, it includes the A solution, or the B solution, or the solution of A and B satisfying at the same time. In addition, the technical solutions of each embodiment can be combined with each other, but it must be based on the premise that the ordinary skilled in the art can realize it. When the combination of technical solutions appears contradictory or unachievable, it should be considered that the combination of technical solutions does not exist and is not within the protection scope of the present application. Based on the embodiments in the present application, all other embodiments obtained by the ordinary skilled in the art without making creative labor are within the protection scope of the present application.

[0047] The technical solutions of the present application will be further described in detail below in conjunction with specific embodiments and the accompanying drawings. It should be understood that the following embodiments are only used to explain the present application and are not used to limit the present application.

[0048] Example 1 Preparation of a copper-decorated porous graphite carbon shell-encapsulated iron catalyst

[0049] (1) 100 mg of dopamine was dissolved in 20 mL of deionized water to obtain solution A;

[0050] (2) 35.5 mg of FeCl3·6H2O and 50.0 μL of ethylenediamine were added to the above solution A, and then the obtained solution was transferred into a reaction kettle, and was heated to react at 160℃ for 2 h. After being naturally cooled to room temperature, the reaction product was centrifuged at 10,000 rpm for 5 min, and was dried in an 80℃ oven for 12 h to obtain solid particles A;

[0051] (3) 0.5 g of solid particles A was dissolved in 100 mL of a 1:1 mixture of water and ethanol at room temperature with stirring at 500 rpm to obtain a clear solution, then 1.0 mL of TMB was slowly injected, stirred for 30 min to form a nanoemulsion system, the reaction product was centrifuged at 8000 rpm for 5 min, washed with water and ethanol three times in turn, and the obtained solid particles were preheated at 350℃ for 3 h, calcined at 800℃ under N2 atmosphere for 2 h at a heating rate of 1℃·min -1 , to obtain Fe@C;

[0052] (4) 0.1 g of Fe@C was dispersed into 35 mL of methanol, then 1 mmol of Cu(NO3)2·3H2O was added, and the mixture was stirred vigorously at room temperature for 24 h, then the mixture was centrifuged at a speed of 5000 rpm to collect the powder, and then the powder was dried in a vacuum oven at 70℃ for 12 h, then the obtained powder was transferred into a quartz crucible and placed in a tube furnace, heated to 850℃ under argon atmosphere at a heating rate of 5℃·min -1 for 2 h to obtain p-Cu / Fe@C (copper-decorated porous graphite carbon shell-encapsulated iron catalyst).

[0053] Example 2 Preparation of a copper-decorated porous graphite carbon shell-encapsulated iron catalyst

[0054] (1) 100 mg of dopamine was dissolved in 20 mL of deionized water to obtain solution A;

[0055] (2) 35.5 mg of FeCl3·6H2O and 50.0 μL of ethylenediamine were added to the above solution A, and then the obtained solution was transferred into a reaction kettle and heated to react at 160℃ for 2 h, after natural cooling to room temperature, the reaction product was centrifuged at 10,000 rpm for 5 min, and dried in an 80℃ oven for 12 h to obtain solid particles A;

[0056] (3) 0.5 g of solid particles A was dissolved in 100 mL of toluene at room temperature with stirring at 500 rpm to obtain a clear solution, the reaction product was centrifuged at 8000 rpm for 5 min, washed with water and ethanol three times in turn, and the obtained solid particles were calcined at 600℃ under argon atmosphere for 2 h at a heating rate of 1℃·min -1 , to obtain Fe@C;

[0057] (4) 0.1 g Fe@C was dispersed into 35 mL methanol, then 1 mmol Cu(NO3)2·3H2O was added, and the mixture was stirred vigorously at room temperature for 24 h. The mixture was centrifuged at a speed of 5000 rpm to collect the powder, which was then dried in a vacuum oven at 70 °C for 12 h. The obtained powder was transferred into a quartz crucible, which was placed in a tube furnace and heated to 850 °C at a heating rate of 5 °C·min-1 under an argon atmosphere for 2 h to obtain p-Cu / Fe@C. -1

[0058] Example 3 Preparation of a copper-decorated porous graphite carbon shell- wrapped iron catalyst

[0059] (1) 100 mg glucose was dissolved in 20 mL deionized water to obtain solution A;

[0060] (2) 35.5 mg FeCl3·6H2O and 50.0 μL ethylenediamine were added to the above solution A, and then the obtained solution was transferred into a reaction kettle and heated to react at 160 °C for 2 h. After natural cooling to room temperature, the reaction product was centrifuged at 10,000 rpm for 5 min, and then dried in an 80 °C oven for 12 h to obtain solid particles A;

[0061] (3) 0.5 g of solid particles A and 1.0 g of 50 nm PS microspheres were dissolved in 100 mL of toluene to obtain a clear solution at room temperature with a stirring speed of 500 rpm. The reaction product was centrifuged at 8000 rpm for 5 min, washed with water and ethanol three times in turn, and then the obtained solid particles B were calcined at 600 °C for 2 h under an argon atmosphere at a heating rate of 1 °C·min-1 to obtain Fe@C; -1

[0062] (4) 0.1 g Fe@C was dispersed into 35 mL methanol, then 1 mmol Cu(NO3)2·3H2O was added, and the mixture was stirred vigorously at room temperature for 24 h. The mixture was centrifuged at a speed of 5000 rpm to collect the powder, which was then dried in a vacuum oven at 70 °C for 12 h. The obtained powder was transferred into a quartz crucible, which was placed in a tube furnace and heated to 850 °C at a heating rate of 5 °C·min-1 under an argon atmosphere for 2 h to obtain p-Cu / Fe@C. -1

[0063] Example 4 Preparation of a copper-decorated porous graphite carbon shell- wrapped iron catalyst

[0064] (1) 100 mg glucose was dissolved in 20 mL deionized water to obtain solution A;

[0065] ​​​(2) To the above solution A, 35.5 mg of Fe(N03)3-9H20 and 50.0 μL of ethylenediamine were added, and then the resulting solution was transferred to a reaction kettle, heated to react at 160 °C for 2 h, after natural cooling to room temperature, the reaction product was centrifuged at 10,000 rpm for 5 min, and dried in an 80 °C oven for 12 h to obtain solid particles A;

[0066] (3) 0.5 g of solid particles A and 1.0 g of a mixture of 1,3,5-trimethylbenzene and polyvinyl-polypropylene ether copolymer were dissolved in 100 mL of a 1:1 mixture of water and ethanol to obtain a clear solution at room temperature with a stirring speed of 500 rpm, then 1.0 mL of TMB was slowly injected, stirred for 30 min to form a nanoemulsion system, the reaction product was centrifuged at 8000 rpm for 5 min, washed with water and ethanol three times in turn, and the obtained solid particles were preheated at 350 °C for 3 h, calcined at 800 °C under nitrogen atmosphere for 2 h with a heating rate of 1 °C·min -1 , to obtain Fe@C;

[0067] (4) 0.1 g of Fe@C was dispersed into 35 mL of methanol, then 1 mmol of Cu(N03)2-3H20 was added, and stirred vigorously at room temperature for 24 h, the mixture was centrifuged at a speed of 5000 rpm to collect the powder, then the powder was transferred to a quartz crucible and placed in a tube furnace, heated to 850 °C under argon atmosphere with a heating rate of 5 °C·min -1 for 2 h to obtain p-Cu / Fe@C.

[0068] Example 5 Preparation of a copper-decorated porous graphite carbon shell- wrapped iron catalyst

[0069] (1) 100 mg of glucose was dissolved in 20 mL of deionized water to obtain solution A;

[0070] (2) To the above solution A, 35.5 mg of Fe(N03)3-9H20 and 50.0 μL of ethylenediamine were added, and then the resulting solution was transferred to a reaction kettle, heated to react at 160 °C for 2 h, after natural cooling to room temperature, the reaction product was centrifuged at 10,000 rpm for 5 min, and dried in an 80 °C oven for 12 h to obtain solid particles A;

[0071] (3) 0.5 g of solid particles A was dissolved in 100 mL of a 1:1 mixture of water and ethanol at room temperature with stirring at 500 rpm to obtain a clear solution, then 1.5 mL of TMB was slowly injected, stirred for 30 min to form a nanoemulsion system, the reaction product was centrifuged at 8000 rpm for 5 min, washed with water and ethanol three times in turn, and the obtained solid particles were preheated at 350℃ for 3 h, calcined at 800℃ under nitrogen atmosphere for 2 h, the heating rate was 1℃·min -1 , to obtain Fe@C;

[0072] (4) 0.1 g of Fe@C was dispersed in 35 mL of methanol, then 1 mmol of Cu(NO3)2·3H2O was added, and the mixture was stirred vigorously at room temperature for 24 h. The mixture was centrifuged at a speed of 5000 rpm to collect the powder, which was then dried in a vacuum oven at 70℃ for 12 h. The obtained powder was transferred to a quartz crucible and placed in a tube furnace, heated to 850℃ under argon atmosphere, the heating rate was 5℃·min -1 , for 2 h, to obtain p-Cu / Fe@C.

[0073] Preparation of a copper-decorated graphite carbon shell-encapsulated iron catalyst

[0074] (1) 100 mg of dopamine was dissolved in 20 mL of deionized water to obtain solution A;

[0075] (2) 35.5 mg of FeCl3·6H2O and 50.0 μL of ethylenediamine were added to the above solution A, and then the obtained solution was transferred to a reaction kettle and heated at 160℃ for 2 h. After natural cooling to room temperature, the reaction product was centrifuged at 10,000 rpm for 5 min, and dried in an 80℃ oven for 12 h to obtain solid particles A;

[0076] (3) The solid particles A were preheated at 350℃ for 3 h, calcined at 800℃ under nitrogen atmosphere for 2 h, the heating rate was 1℃·min -1 , to obtain Fe@C;

[0077] (4) 0.1 g of Fe@C was dispersed in 35 mL of methanol, then 1 mmol of Cu(NO3)2·3H2O was added, and the mixture was stirred vigorously at room temperature for 24 h. The mixture was centrifuged at a speed of 5000 rpm to collect the powder, which was then dried in a vacuum oven at 70℃ for 12 h. The obtained powder was transferred to a quartz crucible and placed in a tube furnace, heated to 850℃ under argon atmosphere, the heating rate was 5℃·min -1 , for 2 h, to obtain n-Cu / Fe@C.

[0078] Preparation of a copper decorated microporous graphite carbon shell encapsulated iron catalyst

[0079] (1) 100 mg of dopamine was dissolved in 20 mL of deionized water to obtain solution A;

[0080] (2) 35.5 mg of FeCl3·6H2O and 50.0 μL of ethylenediamine were added to the above solution A, and then the obtained solution was transferred into a reaction kettle, and was heated to react at 160°C for 2 h. After natural cooling to room temperature, the reaction product was centrifuged at 10,000 rpm for 5 min, and was dried in an oven at 80°C for 12 h to obtain solid particles A;

[0081] (3) 0.5 g of solid particles A and 1.0 g of a mixture of 1,3,5-trimethylbenzene and polyvinyl-polypropylene ether copolymer were dissolved in 100 mL of a 1:1 mixture of water and ethanol to obtain a clear solution at room temperature with a stirring speed of 500 rpm, then 1.0 mL of TMB was slowly injected, stirred for 30 min to form a nanoemulsion system, the reaction product was centrifuged at 8000 rpm for 5 min, washed with water and ethanol three times in turn, and the obtained solid particles were preheated at 350°C for 3 h to obtain Fe@C;

[0082] (4) 0.1 g of Fe@C was dispersed into 35 mL of methanol, then 1 mmol of Cu(NO3)2·3H2O was added, and the mixture was stirred vigorously at room temperature for 24 h. The mixture was centrifuged at a speed of 5000 rpm to collect the powder, and then the obtained powder was transferred into a quartz crucible and placed in a tube furnace, heated to 850°C under an argon atmosphere at a heating rate of 5°C·min -1 for 2 h to obtain D-Cu / Fe@C.

[0083] Preparation of a porous graphite carbon shell encapsulated iron catalyst

[0084] (1) 100 mg of dopamine was dissolved in 20 mL of deionized water to obtain solution A;

[0085] (2) 35.5 mg of FeCl3·6H2O and 50.0 μL of ethylenediamine were added to the above solution A, and then the obtained solution was transferred into a reaction kettle, and was heated to react at 160°C for 2 h. After natural cooling to room temperature, the reaction product was centrifuged at 10,000 rpm for 5 min, and was dried in an oven at 80°C for 12 h to obtain solid particles A;

[0086] (3) 0.5 g of the solid particles A was dissolved in 100 mL of a 1:1 mixture of water and ethanol at room temperature with stirring at 500 rpm to obtain a clear solution, then 1.0 mL of TMB was slowly injected, stirred for 30 min to form a nanoemulsion system, the reaction product was centrifuged at 8000 rpm for 5 min, washed with water and ethanol three times in turn, the obtained solid particles were preheated at 350℃ for 3 h, calcined at 800℃ under nitrogen atmosphere for 2 h, the heating rate was 1℃·min -1 , to obtain Fe@C.

[0087] Preparation of a large-size copper-decorated porous graphite carbon shell- wrapped iron catalyst

[0088] (1) 100 mg of dopamine was dissolved in 20 mL of deionized water to obtain solution A;

[0089] (2) 35.5 mg of FeCl3·6H2O and 50.0 μL of ethylenediamine were added to the above solution A, and then the obtained solution was transferred to a reaction kettle, heated and reacted at 160℃ for 2 h, after natural cooling to room temperature, the reaction product was centrifuged at 10,000 rpm for 5 min, and dried in an 80℃ oven for 12 h to obtain solid particles A;

[0090] (3) 0.5 g of the solid particles A was dissolved in 100 mL of a 1:1 mixture of water and ethanol at room temperature with stirring at 500 rpm to obtain a clear solution, then 1.0 mL of TMB was slowly injected, stirred for 30 min to form a nanoemulsion system, the reaction product was centrifuged at 8000 rpm for 5 min, washed with water and ethanol three times in turn, the obtained solid particles were preheated at 350℃ for 3 h, calcined at 800℃ under nitrogen atmosphere for 2 h, the heating rate was 1℃·min -1 , to obtain Fe@C;

[0091] (4) 0.1 g of Fe@C was dispersed into 35 mL of methanol, then 4 mmol of Cu(NO3)2·3H2O was added, and stirred vigorously at room temperature for 24 h, the mixture was centrifuged at a speed of 5000 rpm to collect the powder, and then dried in a vacuum oven at 70℃ for 12 h to obtain p-Cu' / Fe@C.

[0092] Test method and results

[0093] The catalysts prepared in Examples 1-5 and Comparative Examples 1-4 were subjected to performance test of carbon dioxide hydrogenation to olefins, and the specific test method was as follows: 0.2 g of the prepared catalyst was loaded in a photo-thermal kettle reactor, and the reaction conditions were 200 DEG C, H2 / CO2=3 (molar ratio), 1 MPa, 300 W xenon lamp, and light current density 1.0 W / cm 2 The carbon dioxide hydrogenation reaction was carried out, and the specific test results are shown in Table 1.

[0094] Table 1 Performance test of catalysts for carbon dioxide hydrogenation to olefins

[0095]

[0096]

[0097] As shown in Table 1, the CO2 conversion rates of the catalysts provided in Comparative Examples 1-4 were low, all less than 20%, the CO2 conversion rates of the catalysts provided in Examples 1-5 were high, all more than 60%, and the selectivity of the high-value product C 5+ ＝ in Examples 1-5 was higher than that in Comparative Examples, and the selectivity of the byproduct CH4 was lower than that in Comparative Examples.

[0098] In summary, the copper-decorated porous graphite carbon shell-encapsulated iron catalyst provided in the present application has a novel structure, is used for carbon dioxide hydrogenation to high-efficiency liquid fuel and fine chemicals, has excellent performance, high conversion rate, and relatively optimal selectivity of gaseous products.

[0099] The above is only the preferred embodiment of the present application, and does not limit the patent scope of the present application, and for those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. within the spirit and principles of the present application shall be included in the patent protection scope of the present application.

Claims

1. A copper-decorated porous graphitic carbon shell-encapsulated iron catalyst, characterized by, The catalyst has an iron nanosphere core, a porous graphite carbon shell on the surface, and copper metal nanoparticles loaded on the shell surface. The preparation method of the copper-decorated porous graphite carbon shell-encapsulated iron catalyst includes the following steps: S1. Dissolve the carbon precursor in deionized water to obtain solution A; S2. Add the precursor iron salt and the alkaline catalyst to the solution A, and carry out hydrothermal reaction, cooling, centrifugation and drying to obtain solid particles A; S3. Dissolve the solid particles A and the template agent in a solvent, stir, centrifuge, wash, dry, and calcine under N2 or argon atmosphere to obtain Fe@C; S4. The Fe@C is dispersed in methanol, copper salt is added, and the mixture is stirred vigorously at room temperature, centrifuged and dried, and then calcined under an argon atmosphere to obtain a copper-decorated porous graphite carbon shell-encapsulated iron catalyst. The alkaline catalyst is selected from ethylenediamine and concentrated ammonia. The template agent is selected from one or more of the following: a mixture of 1,3,5-trimethylbenzene and polyethylene-polypropylene ether copolymer, polystyrene microspheres, and polypropylene microspheres.

2. The copper-decorated porous graphite carbon shell encapsulated iron catalyst as described in claim 1, characterized in that, In step S1, the carbon precursor is selected from dopamine, glucose, sucrose, and chitosan; and / or, The ratio of the carbon precursor to deionized water is (100-200 mg): (20-40 mL).

3. The copper-decorated porous graphite carbon shell encapsulated iron catalyst as described in claim 1, characterized in that, In step S2, the precursor iron salt is one or more selected from ferric nitrate, ferric nitrate hydrate, ferric chloride, ferric chloride hydrate, ferric acetate, ferric acetate hydrate, ferric sulfate, ferrous sulfate, and ferric acetylacetone; and / or, The ratio of the carbon precursor to the precursor iron salt is (100–200 mg): (35.5–70 mg); and / or, The ratio of the alkaline catalyst to the precursor iron salt is (50–100 μL): (35.5–70 mg); and / or, The hydrothermal reaction temperature is 160–200°C, and the hydrothermal reaction time is 2–6 hours; and / or, The centrifugation speed is 6000–10000 rpm, the centrifugation time is 5–10 min, and the centrifugation is performed 2–3 times; and / or, The drying temperature is 60–80°C, and the drying time is 12–24 hours.

4. The copper-decorated porous graphite carbon shell encapsulated iron catalyst as described in claim 1, characterized in that, In step S3, the ratio of solid particles A to template agent is (0.5-1g):(1-2g).

5. The copper-decorated porous graphite carbon shell encapsulated iron catalyst as described in claim 4, characterized in that, The template agent is a mixture of 1,3,5-trimethylbenzene and polyethylene-polypropylene ether copolymer, and the ratio of 1,3,5-trimethylbenzene to polyethylene-polypropylene ether copolymer is (2.0-4.0 mL): (1-2 g).

6. The copper-decorated porous graphite carbon shell encapsulated iron catalyst as described in claim 1, characterized in that, In step S3, the solvent is toluene or a mixture of water and ethanol; and / or, The stirring speed is 500–600 rpm, and the stirring time is 30–40 min; and / or, The centrifugation speed is 6000–10000 rpm, and the centrifugation time is 5–10 min; and / or, The washing is performed by washing with water and ethanol sequentially 3 to 5 times; and / or, The drying temperature is 60–80°C, and the drying time is 12–24 hours; and / or, The gas atmosphere for calcination is one of nitrogen or argon; and / or, The calcination temperature is 600–1000℃, and the calcination time is 2–4 hours.

7. The copper-decorated porous graphite carbon shell encapsulated iron catalyst as described in claim 1, characterized in that, In step S4, the copper salt is selected from one or more of copper nitrate, copper nitrate hydrate, copper chloride, copper chloride hydrate, copper acetate, copper acetate hydrate, copper sulfate, and copper acetylacetonate; and / or, The ratio of Fe@C to methanol is (0.1–0.2 g): (35–70 ml); and / or, The ratio of Fe@C to copper salt is (0.1-0.2 g): (1-4 mmol).

8. The copper-decorated porous graphite carbon shell encapsulated iron catalyst as described in claim 1, characterized in that, In step S4, the stirring time is 24–48 hours; and / or, The centrifugation speed is 5000–10000 rpm, and the centrifugation time is 5–10 min; and / or, The drying is vacuum drying, the drying temperature is 60–80°C, and the drying time is 12–24 hours; and / or, The calcination atmosphere is argon, the calcination temperature is 800–1000℃, and the calcination time is 2–4 hours.

9. The application of the copper-decorated porous graphite carbon shell-encapsulated iron catalyst as described in claim 1 in the hydrogenation of carbon dioxide to olefins.

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